The general purpose of our research is to determine the relationship between material structure, membrane function and defects associated with molecular organization into composite membrane systems. Direct micromechanical experiments provide the intrinsic membrane material parameters (e.g. elastic moduli, surface free energy density, etc.) which are the basis for thermodynamic analysis of membrane microstructure. Insight is developed into the alterations of material properties and failure mechanisms in membranes that result from environmental interactions and the normal course of cell life. The specific goals of the proposed research are to: (1) determination of the temperature dependence of the elastic area compressibility modulus and elastic shear modulus of normal red cell membrane -- especially the effects of hyperthermia (37 degress - 50 degrees C) and hypothermia (O degrees - 10 degreesC); (2) study of endothelial cell surface; (3) investigation of altered membrane material structure produced by insemination with membrane bound particles (single-walled, phospholipid vesicles and subsequently influenza virus); (4) study of altered membrane materials structure resulting from immunological reactions of membrane antigens with antibody and antibody plus complement. Coupled with the thermal area expansivity, heats of expansion and extension provide thermodynamic comparison of intact membrane structure for normal and defective membrane states. Micropipette aspiration applied to the membaxrane surfaces of normal and osmotically preswollen cells will be recorded and analyzed on a TV, microscope system; this data provides direct determination of the membrane elastic moduli. The temperature dependence of the material properties will be obtained using a microchamber temperature control covering a range of 0 degrees - 50 degrees C.